Bidirectional Mendelian randomization analysis investigating causal associations between 35 blood and urine biomarkers and oral lichen planus.

Identification of appropriate biomarkers is of great clinical significance for the early diagnosis of oral lichen planus (OLP). The objective of this study was to comprehensively analyze the association of OLP with blood and urine biomarkers. We analyzed the data of 3,63,228 quality-controlled individuals of European origin from the UK Biobank, using 35 blood and urine biomarkers as the exposure group for this study. For the outcome group, we selected data on OLP from the Finnish database. A 2-sample Mendelian randomization (MR) approach was employed, utilizing single nucleotide polymorphisms (SNPs) associated with the 35 biomarkers as instrumental variables to evaluate the causal relationship between these biomarkers and OLP. The inverse variance weighted (IVW) method was implemented as the primary analytical technique, complemented by 4 additional methods: weighted median, MR-Egger, simple mode, and weighted mode. Finally, positive findings will undergo reverse MR validation to confirm the causal relationship with OLP. In this study, we identified a positive association between the incidence of OLP and several biomarkers: albumin (OR = 1.77, 95% CI: 1.19-2.64, P = .005), uric acid (OR = 1.40, 95% CI: 1.03-1.92, P = .034), and vitamin D (OR = 1.70, 95% CI: 1.09-2.65, P = .019). Conversely, we observed a negative correlation between OLP development and urinary creatinine (OR = 0.05, 95% CI: 0.01-0.24, P < .001), Insulin-like growth factor-1 (OR = 0.64, 95% CI: 0.48-0.86, P = .002), and urinary sodium (OR = 0.10, 95% CI: 0.03-0.43, P = .002). Additionally, the reverse Mendelian randomization analyses did not reveal any significant statistical differences between OLP and 6 positive outcomes. Our study provides new insights into the management and treatment of OLP, carrying significant clinical implications.